


Killer x Nightmare (rape)

by CryPainLonely



Series: Sin... about skeletons [1]
Category: Undertale (Video Game)
Genre: Ecto-Body (Undertale), Ecto-Breasts (Undertale), Ecto-Genitalia (Undertale), Ecto-Vagina (Undertale), F/M, Forced Orgasm, Rape, Rape/Non-con Elements, Sex, Sex Toys, Tentacles, Vaginal Sex
Language: English
Status: Completed
Published: 2020-12-01
Updated: 2020-12-03
Packaged: 2021-03-09 23:21:52
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 2
Words: 3,933
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27824449
Author URL: https://archiveofourown.org/users/CryPainLonely/pseuds/CryPainLonely
Summary: My oneshot about Nightmare fucking killer. Im sorry.Mostly just reuploading from my wattpad
Relationships: Nightmare/Killer, Sans/Sans (Undertale)
Series: Sin... about skeletons [1]
Series URL: https://archiveofourown.org/series/2036245
Kudos: 32





	1. Part 1 lol

Nightmare was in his office, sipping on some cold tea. Papers and other things around him and on the floor. The last few days didnt go well. And not because of his brother and his weird friends. It was because of killer. The tarleaking skeleton met color a few days ago. And it was bad. Killer started rebelling. Yes, he already did that before, but only if nightmare forgot to corrupt his soul. But now it was every day. And it was getting on Nightmares nerves. There had to be something to do right? Probably not. The mind was the hardest to corrupt. ˋIf that fucking rainbowhead hadnt met killer, this wouldnt have happend! And now he has hope. The one thing that can reverse my magic'Nightmare thought.

Nightmare continiuted ˋSo I need to get that hope out of him... FORCE it out... but how...' Nightmare, now deep in his thoughts, did not notice the time untill... A knock came from the door. It was rough and quick, the sound echoing in the empty dark room, filling it with a sound other then the sound of Nightmares goo and the ticking of a clock on the wall. Nightmare could tell it was Dust. But where they already back? It was just twenty minutes ago that he sent them awa- a quick look to the clock on the wall proved him wrong. They where gone two hours. Nightmare probably gone too. "Come in." Nightmare said.

The door opend and Dust stepped inside. His breathing was low ,to low, almost like he was triyng to calm down. And Nightmare knew. "You failed, am I right?" Nightmare asked, his visible eye staring intense at him. "Sit down" Nightmare commanded, still staring at him. Dust did as he was told, not wanting to anger the one in front of him. Dust could clearly tell he wasnt in a good mood. "Should i close the door or-" "No need to" Nightmare interupted.

Then there was a long pause. And even with the door open, the air felt heavy. "S-so at first everything went as planed..." Dust started, wanting to fill the silence. "We went to ScinceTale, found the starsanses and fought... halfway through, when I tried to attack dream, I got attacked by killer-" "So he snapped again?" Nightmare asked. Dust just nodded. "Is he calm now?" Nightmare continiuted asking him. "He is still like this... but he doesnt attack anyone. Think he went to his room..." The last words where only mumbled. Nightmare groaned. "Dust, I want you to bring Killer here. Im gonna... talk to him." Nightmare orderd, his voice shaky, trying to not lash out on Dust. The other only nodded, then stood up and left the room, closing the door behind him. And now the room was dark again.

What was he supposed to do now? He needed to stop Killer from this. From wanting free. If Nightmare could just break him... he could. ˋYeah...'Nightmare thought. ˋIm gonna show him who the boss is. But how... ' Nightmare now just needed to know how to break him. He could torture him, but Killer had a high resitence against that. Or he could just try something new... He could do things to him. Show him whos in controll... and then it was decidet. He was gonna rape the other. (How do you get to this conclusion??) 

Now Nightmare was just waiting for him to show up. And after a few minutes he did. Nightmare could already feel his presence. His Emotions they where full of... annoyance? He was annoyed? This fucking Skeleton was annoyed? This made Nightmare angry. Really angry. "Come in" Nightmare said, trying to sound calm. And the door opend. "I didnt even knock." Killer said, his voice a mix of boredom and annoyance. Nightmare only glared at him. He then pointed to the seat in front of him. Nightmare didnt want to say anything, fearing he could snap. I mean yeah, he was going to do that, but the door had to be locked first. 

Nightmare stood up. A silver key in one of his tentacles. Going torwards the dark wooden door, he closed it, making a loud klicking noise. Afterwards he put the key into one of his pockets. Killer felt weird. Scared even. Something inside of his empty ribcage was telling him to run. Killer ignored it. He knew his boss was angry. And he knew that nightmare knew that killer still was able to feel emotions. I mean it was obvious, his soul currently in heart form.

Nightmare turned around, facing killers back. He then took a few steps forward untill he was behind killer. "So whats my punishment? Gonna break my bones? Burn them?" There was a long pause again, letting killer drown in the silence. The air was heavy. The ticking of the clock getting louder with each sound. After a minute or two Nightmare finally spoke up. "Strip." the command was simple, Nightmares voice cold and clear, cutting the silence like a knife. "What? Why shou-" "Strip." Killer asked but was cut off by Nightmare. His voice now louder and clear.

"Uhhh... ok?" Killer replied, his voice confused and unsure. With that, killer stood up and began to remove his jacket. Killer looked at nightmate, his hands ready to also remove his t-shirt, but still unsure. "Everything. Including your underwear." Nightmare said, his voice still strong and cold. And like killer was told, he did. After a minute he was only standing in his underwear, clearly uncomfortable. His clothes where in a messy pile next to the chair he was sitting in and after a few seconds, his underwear joined.

"And what now?" Killer asked, clearly still confused. Killer was shaking a little due to the cold air in the dark room. "Summon your female ectobody." Nightmare grinned at killer who stared at him only for a while, his bad gutfeeling now screaming at him to just run. But he didnt. Instead he just complied with the order again. Any other monster would have been running by now. But killer knew that Nightmare was way more stronger than him. The space between his bones filled out with red glowing magic, forming into his female form. 

After killer was done, Nightmare suddenly slammed him onto the table with one of his tentacles. The tentacle then released killer, letting him sit up. Nightmare took seat on the chair killer had sit on before, now being in eyelevel with killers bottom area. "Spread your legs and masturbate. The more you are prepared, the less its gonna hurt."  
Killer cringed. He knew he would get punished. He expected to get some of his bones broken, shure, but this? This was beyond humilliating. This was too much. Even for him. 

Killer shakily shook his head. He wouldnt do this. He couldnt do this. Nightmare looked at him for a few seconds before teleporting out of the room, leaving killer alone in the dark office. Around five minutes went by. Killer was already silently panicking, knowing what was going to happen to him. And he didnt like it one bit. Nightmare teleported back into his room, holding a phone in one hand and a bullet vibrator along with a dildo.

Nightmares tentacles lashed out again, two spreading killers legs and a third one holding killers neck, forcing him to look at the celing. Nightmare sat down on his chair again. Suddenly Killer felt cold hands on his stomach, that were slowly gliding down from his ectostomach to his privat part. (I am sorry, i cannot bring myself to write it.) Killer was shaking, both from fear and the cold temperature. When Nightmares hand got down, he at first brushed his finger gently against killers clit.

Killer was still dry, but it didnt matter to the other. Nightmare took his indexfinger and thumb to spread killers fold. Killer was scared. He didnt want this. And what made it worse was the fact that he couldnt even see what was happining. He could only look at the celing and hope that his boss would have mercy. Killer twitched when suddenly, something round and cold was pressed against his clit. "Who do you belong to?" Nightmare asked, his voice cutting trough the silence like a knife. Killer pressed his head down, looking at Nightmare, the tentacle relaxing a bit. Killer thought for a while. 

"Nobo-" Killer was cut of by the vibrator, wich now started to vibrate. Killer let out a loud and long moan, before biting on his lips in an attempt to stop the noise. Killers hands were griping onto the table, marking it in the proces. Nightmare turned the vibrator on its lowest setting, giving killer time to breathe.

Nightmare took one of killers hands and pressed it against the vibrator. The tentacle around his troat forced killers head up again. Killer let out a confused whine. "Hold it against your clit. If i see you taking it off, i will punish you more. Understand?" Punish him more? What more could he do to him? Kill him? Killer was fine with that. Anything was better than this. 

Killer took the bulletvibrator into his hand and pressed it against himself, making him whimper. He didnt want to know what Nightmare would do to him. So he gave a slow nod, closing his eyes. Nightmare turned the vibrator back on, higher than before. Killer moaned loud, not being able to stop the noises. When killer looked down, he could see Nightmare holding the Phone the other brought. Nightmare was filming him. 

When Nightmare noticed that, the tentacle around his troat tightend and pressed his head up again. Suddenly the vibrator went higher, making killer moan loud, almost screaming. After a few seconds, Nightmare turned the vibrator down. Then higher again. The darker continiued to change between the high and low setting. Killer moaned and huffed, squirming on the desk. Then he felt preasure in his lower stomacharea. Like a bubble that was growing. Killer closed his eyes and bit his lip, untill it was bleeding. 

Then he came. He jumped, his back arching. Twitching and shaking he moaned out loud, knowing the outside world behind the closed door was able to hear everything. The orgasm hit hard, letting killer see stars in his eyes. Killer tried closing his legs, though of course Nightmares dark, goey tentacles wouldnt let him do so. Why would they? Killer came down from his high and so did the vibrator, though it stayed on its lowest setting instead of being turned off. 

Nightmare decidet that he would still give killer a second chance at changing his mind. So he asked again. "Who do you belong to?" The question was simple, only one word needed to awnser. But killer didnt. He hadnt lost all of his pride yet. Yet. Moving his head wasnt an option dze to the dark apandege, holding it still. So instead killer just closed his eyes and gave into the silence, letting the tiking of the clock be, again, the only thing to fill the room. Though killer rather wished for the clock to be gone. 

The ticking wasnt helping at all, its regular sound stressinducing. This was a nightmare. And killer wanted to wake up. But he didnt. Because this was no simple dream, no this was reality... this was live and it was spitting right into his face., moking him. 

"Should i take this as a no? That you dont understand who you belong to?" Nightmare asked, his tentacle releasing its grip on killers head, allowing the empty-eyed skeleton to move uts head freely again. Killer stared down at his boss, panting heavily. He opend his mouth, ready to speak. "Yes. Take this as a no. I dont belong to you." Killer said with all that he had left, calm like he was in his emotionles state again. Exept he wasnt. And that pissed the black skeleton off more then anything else. How dare he? How dare he speak this way to his boss? His king? The one that saved him from the endless genocide of his own home?

Hitting the 2000 word mark here. I will continiute this in another chapter, if you have any suggestions, feel free to tell me and i look at what i can do... byby.


	2. Part 2

"Should i take this as a no? That you dont understand who you belong to?" Nightmare asked, his tentacle releasing its grip on killers head, allowing the empty-eyed skeleton to move its head freely again. Killer stared down at his boss, panting heavily. He opend his mouth, ready to speak. "Yes. Take this as a no. I dont belong to you." Killer said with all that he had left, calm like he was in his emotionles state again. Exept he wasnt. And that pissed the black skeleton off more then anything else. How dare he? How dare he speak this way to his boss? His king? The one that saved him from the endless genocide of his own home?

There it was again. That heavy feeling in the empty room, making killer drown in the silence. Only the rythmic ticking of the clock was letting killer know that he hadnt gone deaf. He wasnt breathing, holding it back in fear of what would happen. He had messed up. He knew that. That was why he was here after all. Because he made a mistake... no. That was what Nightmare wanted. For him to regret it. To obey to his king again. To know who he belonged to. He belonged to himself. Nobody could take that away. Right?

Nightmare growled, his tentacle wrapping around the other s throat again as he lifted the poor skeleton into the cold air, hands and feet struggeling to hold onto something as he kicked into the smooth side of the table, trying to shift his weight onto something else then his neck. Killer was panting loudly, trying to get to the air that he didnt need. His hands shot up, white fingers digging into the dark tentacle, a little thud being heard from the ground as the vibrator fell onto the wooden floor.

It didnt do much though, only making Nightmare angrier as he squeezed killers airways shut. Nightmare chuckled a bit, his energy growing as it fed off the others fear and pain. Nightmare took the dildo and placed it upright onto the wooden table, two of his fingers holding the base so it wouldnt fall over. He then let the tentacle around killers throat loose, making killer fall onto the dildo, it slipping right in.

There was a loud screech when it was inside of him, killers eyes shutting themselfs. It was a delicios mix of pain and pleasure, something he wished wasnt the case. His hands were still clawing on the tentacle, trying to get it loose. Of course that didnt work, but killer didnt care. All he knew was that he had to get out of here. Out of this empty room, out of this drowning silence and away from this cruel monster he called his boss. There was a little pause, the tentacle tightening around killers throat again but not enough to choke him.

Killer was panting, his ribcage rising and falling again as he filled his non-existend lungs with air, trying to get back energy. The objekt inside of his was making him uncomfortable, every breath or little movemend letting it brush his insides gently. The tentacle forced his head up in the air again, letting Nightmare go out of his viewpoint as he stared at the wooden ceeling. 

Nightmare picked up the little bulletvibrator that the other had thrown on the ground a minute ago, picking it up and pressing it against killers clit again. "You can choose. A: you hold it again and be a good pet or B: you dont and i'll stuff it into your little cunt and turn it on and wait an hour. You can decide." Pet? That was what Nightmare saw in him? A pet? Killer shakily reached to his clit to hold the vibrator, pressing it against himself. Nightmares hand wanderd up, holding killers wrist and stroking the others hand gently with his thumb. 

Nightmares tentacles wrapped around the others legs and tighs, another around his waist. They then gently lifted killer up before slamming him down onto the dildo, making killer moan out loudly as he closed his eyes. The bulletvibrator started to vibrate gently against the other, stimmulating the other. His lower region felt like it was on fire. Not in a bad way, wich made killer cringe at himself. His body was enjoying this. He wasnt though.

Killer started to moan as Nightmare lifted and pressed his body into the dildo again. And then again and again untill Nightmare found a rhythm that he liked. Killers other hand was digging into the wooden table again, trying to grip on something. The tentacle around killers throat retreated, letting killer fully breath again. The first thing killer did was stare down at Nightmare. Nightmare had wide eyes as he stared in facination at the others entrence his hand continuing to stroke the others. 

The tentacle went around killers breasts, giving him extra support as killer leaned backwards, his head turning to the side to stare at the dark wall. The sounds of moaning and pantind along with the vibrating sound of the toy were all that was filling the quiet, empty room.

Nightmare turned the setting of the vibrator higher, making the other moan loudly as Nightmare thrusted his body into the dildo. Killer could feel another orgasm building up, preassure rising like a bubble. Nightmare noticed and opend his mouth to speak. "Hold it." Its was a simple command, easy for killer to understand. Killer started to squirm, trying not to cum. Nightmare thrusted the other into the dildo faster, making killer whine as he tried to keep himself together.

"Who do you belong to?" Nightmare asked, turning the vibrator higher, making killer shake. He was so close, like a cup that was threatening to overspill the moment even one more drip was added. Killer leaned foreward, his head over Nightmares as he stared down at the other, mouth open as he moaned loudly. "I-i... uhhh... fuuuck..." killer tried to speak, but failed.

Stringing together sentences was hard, like he forgot how to speak, only moans comming out of his mouth. "T-to yooouu..." killer tried to speak. What was he fighting against when he got here? What made him so scared... was he scared in the first place? He couldnt remember, only concentrating on trying not to cum. "Who owns you?" Nightmare asked, his other hand wrapping around killers and gently stroking it with his fingers. Killer pressed into the others hand, trying to concentrate trough all of it.

Killer took a few seconds but finnaly spoke. "Toyouuu... N-nightma-affffuck..." killer was interupted by his own long moan as he came. It felt like heaven. For a few seconds he wasnt in the dark office anymore but in a cloudy sky. Killer was twitching back and forth, his vision already having gone dark. Nightmare turned off the vibrator and took it out of killers weak hands, laying it on the wooden table.

Finnaly, killer came down from his high, shaking and twitching as his body was held by Nightmares tentacels. He fellt like a liveless doll as he had no energy left to move his limbs. He just layid there panting loudly trough his mouth in order to get the most air. He was tired and wanted to leave. Just sleep perhaps... just close his eyes and relax...

"Dont fall asleep yet, im not done." Killer opend his eyes again, tiredly looking at Nightmare. He couldnt remember closing them in the fist place. And what did he mean with... oh no. Not more. He couldnt handel that. Killer shook his head, whining as he did so with the little energy he had left. His head felt so heavy, like somebody put stones into his empty skull. Nightmare chuckled a bit as he lifted killer off the dildo wich right after fell to the ground with a loud thud. Nightmare then laid killer onto the table, spreading his legs wide so he could get between them.

Nightmare had an obvious cyan bulge in his pants and killer could see it. He couldnt handle that. He couldnt handel anything more at the moment. The darker hooked his finger into his pants in order to pull them down just a little, letting his cyan dick free from its little prison. He then rubbed the tip of it against killers entrence, slicking it up for what was about to happen.

Nightmare pushed in whilest leaning forward, groaning into the others ear. Killer himself gave a loud yelp from himself as he could feel everything that was happening. Nightmare quickly started thrusting, hitting the others g-spot dead on. Killer was moaning quietly, his arms laying to his sides unmoving, not having the energy to do anything at all. Killer felt awfull, too cold but too hot at the same time as if he was sick. He wished he was. That he was just sweating in his own bed as he dreamed of this horrific nightmare. It wasnt.

Killer stared to the side, thinking about how nice it would be to be in his room. Or perhaps with Horror, gling hunting... phisically he was in the room. But his head was elsewhere, trying to blend what was happining to him out. Something small moans came from killers dry throat, but that didnt bother him anymore. But he was shaken out of his mentall bubble as he could feel sharp fangs digging into his shoulder, past the surface of his white bones, letting red blood come out. Nightmares started to speed up, groaning into the others dammaged shoulder as he did so. Killer came again, twitching a few times before he could feel something.

Warm cum gushing into his womb, filling him. Some of it flushed out, making the table more dirty then it alredy was. Killer could only lay there, body still numb as he took all of it. Nightmare pulled out his teeth, red blood flowing down the white bone and onto the wooden table. Nightmare then pulled out of killers entrence, cyan cum following and pripping down killers tighs and onto the table.

Nightmare took two fingers and whiped the cum off the table before stuffing it into killer. He did that again untill there was no cum left outside, all of it inside of the poor skeleton underneath Nightmare. Killer opend his mouth, trying to say something. "I'll... no... i'll get pregnant..." killer whisperd, all of his voice gone at this point. Nightmare chuckled, grinning at the other. "Thats your punishment... but dont worry... i wont let you give birth if it comes so far..." Nightmare laid his hand on killers cheek, stroking it softly. He then stood up, pulling his pants back in place at the same time.

Nightmare took the little key of the locked door and laid it besides the panting killer. "Here. Im done for today. You may stay in my office for a while, but be warned. If i see you still in here and am in the mood again, i might just try something again." Nightmare had a big grin on his face. He then snapped his fingers, leaving killer alone in the big, dark, emty room. Alone. In pain...


End file.
